Sol-gel derived multilayer antireflective coatings fabricated at room temperature using nonthermal oxygen plasma

Sol-gel preparation of multilayer antireflective (AR) coatings is important for low-cost and large-scale optical and solar applications. Current method relies on calcination to remove organics and form inorganic phases with desired optical properties, which often results in diffusion at the interface, reducing the coating's functionality. Also, the high temperature treatment is not compatible with the development of flexible electronics using heat-sensitive substrates. In this work, we show the fabrication of bilayer AR coating composed of glassy SiO₂ and crystalline TiO₂ at ∼35 °C via oxygen plasma processing of sol-gel films. The processed coatings show smooth surface morphology and sharp interfaces between different layers, thereby, avoiding abnormal particle growth and interfacial diffusion occurred during calcination. The bilayer AR coating prepared by plasma treatment exhibits superior visible transmittance and hydrophilicity while maintaining comparable hardness to calcined coatings. Plasma treatment effectively prevents thermal diffusion, ensuring better structural integrity.